A. FIELD OF INVENTION
This invention relates to an apparatus for operating a garage door and the like, and more particularly to a screw drive type of operator.
B. DESCRIPTION OF THE PRIOR ART
Apparatus for opening and closing garage doors or garage door operators have been manufactured and sold for many years. These operators have been designed to move a garage door automatically from a substantially vertical position to a substantially horizontal position and return again. Garage door operators are now commercially available in kits for the home improvement market. The kits generally consist of an A.C. motor, a support rail, a drive mechanism such as a drive screw and a traveler.
When all of the components of the kit are fully assembled, the drive screw is disposed in and supported by the rail, and the traveler is attached to the door and mounted on the rail to engage the drive screw. The motor operates the drive screw to reciprocate the traveler along the rail to selectively move the door from a vertical position to a horizontal position or vice versa. In an attempt to reduce the size of the package for shipping purposes, the drive screw and the support rail are constructed in segments which are attached together manually prior to installation. Such segmented screws are disclosed for example in U.S. Pat. No. 4,352,585.
These existing kits however have several problems. First, the drive screw segments are coupled by coupling mechanisms including screws, spring pins and holders which are not only difficult to assemble but are subject to large torsional forces and wear and tear during operation. Second, these door operators lack proper means for providing continuous lubrication for the drive screw and traveler over long periods of operation. Third, these door operators include a mechanism for defining the length of travel of the traveler for a particular door which is much too complicated for the average consumer to set. Moreover, these mechanisms are unreliable.